Assessment of physician compliance to liver function test monitoring guidance for patients treated with lapatinib

Abstract

Background and objective A cumulative review of hepatobiliary abnormalities in the lapatinib clinical program resulted in inclusion of detailed instructions for liver function test (LFT) monitoring in the US prescribing information (label). We sought to determine whether or not physicians adhere to these recommended guidelines. Methods A retrospective observational cohort study comprising 396 women with HER2+ metastatic breast cancer who initiated lapatinib between March 1, 2007 and June 30, 2010. Data were captured from electronic medical records (EMR) of communitybased oncology practices. Patients were categorized by whether they initiated lapatinib before or after the label change; LFT monitoring was evaluated using a pre-versus post-label study design. We measured the proportion of patients who had LFTs within 30 days before lapatinib initiation, LFTs during each 6-week period of treatment, and lapatinib permanently withdrawn after experiencing an extreme LFT elevation. Results Among 396 patients, 128 (32%) initiated lapatinib pre-label change, and 268 (68%) initiated post-label change. LFTs were conducted 30 days prior to lapatinib start in 82% post-label versus 63% pre-label change patients (P = .001). Testing during each 6-week treatment interval was higher in post-label change patients: 81% versus 68% pre-label change patients during the first 6 weeks of therapy (P < .004), and 83% versus 62%, respectively, during weeks 18-24 (P = .0103). Four patients experienced a severe LFT elevation: 2 pre-label patients who resumed treatment, and 2 post-label change patients with complete discontinuation. Conclusions We demonstrated that LFT monitoring increased after the addition of detailed LFT guidance to the lapatinib label. © 2013 Frontline Medical Communications.